Conventionally, there has been provided a contact device in which, for example, an airtight (sealed) space is formed with a box-like housing (a box-like sealed vessel), and contact portions are housed in the airtight space. With the contact device of such a kind, in order to secure insulation, airtightness, and heat resistance, the airtight space is defined by a housing made of ceramic, for example. However, since a ceramic-made housing tends to contract when sintered, it is difficult to improve dimensional precision.
On the other hand, there has been proposed a contact device (a contact switching device) in which the airtight space is formed by integrally joining a ceramic plate, which holds fixed terminals (fixed contact terminals), and the upper opened edge of a metal tubular flange to each other (see Patent Literature 1, for example). Patent Literature 1 discloses that higher dimensional precision can be secured by a combination of a plate-like ceramic (a ceramic plate) and a metal tubular flange as compared to the case where a box-like ceramic is employed.
Further, in a contact device (a magnet switch for a starter) disclosed in Patent Literature 2, fixed terminals (fixed contacts) are fixed to an insulating contact case in the state where the fixed terminals penetrate through the side surface of the insulating contact case and clamp the insulating contact case. Here, at the side surface of the insulating contact case, conical through holes are formed for the fixed terminals to be inserted and disposed. In the through holes, heat-resistant insulating spacers made of a ceramic-base material are disposed. By the fixed terminals being inserted into the heat-resistant insulating spacers, they are indirectly held to the insulating contact case. Further, according to Patent Literature 2, the insulating heat-resistant spacers are conical in shape, and just tightening the fixed terminals causes the fixed terminals to be disposed concentrically.